High-current inductors are needed in many power converter applications, such as, for example, an output filter inductor for a dc-to-dc converter. Inductors for dc-to-dc converters typically employ a ferrite magnetic core and copper windings, and such inductors typically have a significantly larger dc current component than ac current component. AC flux is limited by the thermal characteristics of the core material and the resistance of the windings. Disadvantageously, the thickness of copper windings is limited by the ability to wind about the core, and the magnetic core must be sized to contain both the ac and dc magnetic flux.
Accordingly, it is desirable to provide an inductor structure that overcomes the structural limitations described hereinabove. Such an inductor desirably has a very high window area fill factor, repeatable electrical characteristics, and well-contained magnetic fringing flux. Furthermore, such an inductor should be simple to construct in order to be practicable.
A high-current inductor is constructed using two single-sided or double-sided printed circuit boards having patterned copper traces thereon, a magnetic toroidal core, and multiple interconnecting wires extending between the boards. Multiple turns for the inductor are created by suitably configuring the copper traces on the printed circuit boards. Vias are employed on each circuit board for electrically interconnecting the boards to each other. Multiple thick, solid-gauge wires are situated in the vias in order to provide a very large copper area, thus providing high current carrying capability.